Some attempts have been made to provide environmental control systems and apparatus for buildings, for example:
U.S. Pat. No. 4,429,735 to Nomaguchi for a Simplified Air Conditioner includes a suction blower and an exhaust blower. The suction and exhaust blowers are driven by a common electric motor which is mounted between the blowers. The blowers are mounted in suction and exhaust passageways, respectively. The suction passageway crosses the exhaust passageway in a heat exchanger and is connected to an indoor exhaust port. This apparatus provides a rudimentary heat exchange between the intake and exhaust air streams, but fails to provide any environmental humidity control.
U.S. Pat. No. 6,752,713 to Johnson for a Cool Air Ventilation System shows a system of ducts which draw cool air from a ventilated basement or crawl space to an attic using a blower. The cool air flows into the attic through a vertical conduit and forces the attic air outside the building through exterior attic vents. This system fails to provide adequate humidity control in the living space between the basement and the attic.
U.S. Pat. No. 6,319,115 to Shinguki for an Air Cycle House and House Ventilation System shows a house having an indoor space which is enclosed and thermally insulated by an underfloor insulating space and a ceiling insulating space. Outdoor air is drawn into the indoor space from an air intake and air is expelled from a ceiling ventilation layer into an under roof space by a ventilation fan and then discharged outdoors. A heat exchanger mounted in the ceiling ventilation layer facilitates heat exchange between air in the ceiling ventilation layer and incoming fresh outdoor air. After the heat exchange process, the incoming air is delivered into the underfloor ventilation layer. However, this “air cycle house” has the disadvantage of requiring large spaces above and below the living space, e.g., ceiling ventilation space and underfloor ventilation space. The air from these spaces, which may be of inferior quality, may enter directly into the living space. Furthermore, this system also fails to teach the control of humidity.
U.S. Pat. No. 3,656,542 to Darm for a Ventilating System for Compartmental Buildings shows a simple air-to-air heat exchanger which supplies fresh air to regulate the delivery temperature of the air.
U.S. Pat. No. 4,590,990 to George for a Ventilation Heat Recovery System includes a shell and tube heat exchanger. Air is drawn from the ambient atmosphere into the shell for heat exchange flow counter to exhaust air that is drawn from the building atmosphere and forced through the heat exchanger tubes prior to exhausting to the atmosphere. An annular-shaped distribution channel includes distribution orifices for distributing incoming air into the building atmosphere.
Similarly, U.S. Pat. No. 4,794,980 to Raisannen for an Air-To-Air Heat Exchanger shows a heat exchanger which includes circular ducts with cone shaped turbulators. The turbulators are intended to enhance heat exchange between air flowing in a pair of concentric ducts.
Above referenced U.S. Pat. Nos. 3,656,542, 4,590,990 and 4,794,980 teach simple air-to-air heat exchange in a ventilation system with no concurrent control of the humidity in the air.
U.S. Pat. No. 4,040,804 to Harrison describes a heat and moisture exchanger consisting of a folded sheet of water permeable paper. Air is directed in one direction through the folds on one side of the folded paper. The return air flows in the opposite direction through the folds on the other side of the folded paper. Water and heat are simply transferred through the paper from one air stream to the other air stream flowing in the opposite direction.
U.S. Pat. No. 4,210,278 to Obler describes an apparatus for supplying conditioned air at a substantially constant temperature and humidity. A supply duct carries the supply air. A return duct is coupled to the supply duct for carrying return conditioned air. An air conditioner is coupled to the supply duct for decreasing the temperature of the supply and return conditioned air. A by-pass duct is coupled to the supply duct for selectively directing portions of the supply and return conditioned air around the air conditioner. Another bypass duct is coupled to the return duct for selectively directing portions of the return conditioned air around the supply duct and the temperature reducing device. Although controller devices are used to control the flow and amount of mixing of the supply and return conditioned air flowing through the air conditioner and within the supply duct, no heat or humidity exchanger is used.
U.S. Pat. No. 6,131,653 to Larsson describes an air dehumidifying and conditioning system which draws incoming air through a fan and uses heat from the fan and fan motor to heat air discharged from the fan. The system then divides air discharged from the fan into a supply stream and a scavenge stream. The supply stream is passed through a pre-cooler and an air cooler for cooling and dehumidification. The dehumidified air of the supply stream is then heated by passing through a heat exchanger, with the heating by the heat exchanger being accomplished using the scavenge stream. The dehumidifying function of this system relies solely on the air cooler, and does not use any humidity exchanger.
U.S. Pat. No. 6,622,508 to Dinnage et al teaches an apparatus and method for heat and humidity exchange between two air streams, one hot and one humid. A first air stream is fed from the interior of a building to the ambient air and a second air stream is fed from the ambient air to the interior of the building. The first air stream is cooled and transferred through a heat exchanger, to a heater and a dehumidifier before being exhausted to the ambient air. The second air stream is transferred through the dehumidifier and the heat exchanger, whereupon it is cooled in a cooling device before being transferred into the interior of the building. Before being fed to the dehumidifier, the second air stream is caused to exchange heat and humidity with the first air stream before the latter is fed into the heat exchanger. This method, by using a regular heat exchanger attached to a dehumidifier, however, limits the heat exchange stage and the humidity exchange stage in series, thereby requiring the use of additional cooling functions. Furthermore, due to the serial design of this apparatus it is difficult to control the enthalpy exchange and the heat exchange separately by using, for example, an electronic controller.
U.S. Pat. No. 5,092,520 to Lestage, relates to an air extraction apparatus for conditioning air in an enclosed space. The air in the enclosed space is stratified due to a temperature gradient between a ceiling and a floor of the enclosed space. The apparatus has a conduit with an inlet end and an outlet end. The conduit may be arranged and installed with its outlet end in communication with an opening in a wall of the enclosure and its inlet end in proximity to the floor when in use. A fan may be used in the conduit to effect movement of air from the floor level of the enclosure through the inlet end to and outwardly of the outlet end. A controller is used to control the operation of the fan by being responsive to a selected condition, e.g., relative humidity of the air in the enclosure.
Building construction methods and materials currently in use, especially the increased utilization of thermal insulation layers and moisture barriers have resulted in more air-tight construction to the point where supplementary ventilation has become a necessity in order to maintain air quality and humidity control within a building. This condition exists both in new building construction, or after building renovation using the state-of-the-art standards and technologies which result in relatively air-tight construction. Such air-tight building construction may cause interior environment problems.
The natural movement, or infiltration of hot humid air, from either the outside of a building or from upper levels of a building into a lower level of the building, for example, basement or crawl space, where temperatures are lower, can lead to condensation causing mold formation and odors, with resultant health issues as well as structural damage. For example, infiltration of the humid warm air into wall cavities during the summer, which is caused by constant cooling of the air mass, and the reduction in volume of the air mass, with resulting prolonged negative air pressure within the building, can result in mold formation. Mold and mildew conditions are considered health hazards and are considered to contribute to various respiratory conditions, including asthma, especially in children.
The infiltration of warm humid air may also result in increased air conditioning requirements with increased energy usage.
Current building ventilation systems do not address the issues related to negative air pressure within a building. These current building ventilation systems have a negligible ability to mitigate the effects of basement and crawl space humidity and condensation, especially during periods of high outdoor temperature and humidity.
Dehumidifiers are often used to address localized humidity problems. However, these devices are costly to operate and they do not address the issues of indoor air quality.
As well, during periods of prolonged and extreme conditions of high humidity or temperature, either hot or cold, the temperature and humidity levels of the air supply delivered by the ventilation system is such that the operation of the system requires expenditure of significant energy and cost in order to maintain reasonable levels of comfort
Therefore, despite the developments of the prior art, there remains a need for an effective and efficient heat transfer, humidity and ventilation control apparatus for use in buildings. In particular, there is an unmet need for a balanced air circulation system using the basement's natural environment which controls humidity, enables efficient energy recovery from air conditioning and heating systems, and boosts the energy efficiency of air conditioning and humidity control systems during outside conditions of high temperature and high humidity while providing the necessary ventilation requirements.